A scale and two different distance questions

An original fictional map-reading exercise uses a flat plan with a scale of 1:50000. A straight segment between two marked points measures 3 centimeters on the plan, while a drawn curved route between the same points measures 4 centimeters. The exercise asks for horizontal ground distances represented by those two measurements. It supplies no terrain-gradient model, current access permission, transport conditions or operational task. A learner treats the straight segment as if it were necessarily the distance traveled along any available route. The aim is to keep units, geometry and the question being answered separate, without turning an arithmetic exercise into a recommendation for movement or a claim of safe passage.